If you give plenty of quizzes you might want to consider using "immunity" from one of those quizzes as a reward or prize for some other activity.

For example, suppose you are playing bingo and you want to award a prize to your students for winning, you can grant them "the immunity idol" the possessor of which is exempt from the next quiz (they get 100% on the quiz without taking it).

Tips: 
This works well if you give many smaller quizzes.  I wouldn't use it for midterms or finals or any other substantial testing process. You need to maintain the integrity of your course.